1. Field of the Invention
This invention relates to a camera with programmed exposure control and more particularly to a camera wherein exposure is controlled according to subjectively determined and stored corresponding combinations of aperture values and exposure times for each of various exposure values.
2. Description of the Prior Art
It is well known that two kinds of exposure control are used; one wherein a combination of an aperture value and an exposure time is selected for a particular exposure value each time photographing is effected and the other wherein all of the combination of aperture value and exposure times are predetermined for individual exposure values in order to assure easiness of operation. A socalled manual exposure control is a typical example of the former, and an automatic exposure camera wherein a preferred one of exposure time or aperture value is changed every photographing also falls within the concept of the former. On the other hand, an example of the latter type is an aperture-preferred or exposure time-preferred automatic exposure camera in a normal of operation wherein a preferred one of the exposure information is fixed at a particular value in advance of photographing. In other words, this mode can be regarded as an exposure control wherein all combinations of the aperture values and exposure times are predetermined for individual exposure values, because one of the aperture value and exposure time is known in advance from a one-to-one relationship with any exposure value when the other is fixed at a particular value. A programmed automatic exposure control method to vary both the aperture value and exposure time in a given relationship with variations in the exposure value also belongs to the latter type of exposure control systems.
When the term "program line" is used (throughout the present disclosure) it should be understood to represent a possible variation in both the aperture value and exposure time, in combination, in response to a variation in the exposure value, the program line can vary depending upon the exposure control method of various cameras. A discussion on the comparative merits of an exposure time-preferred camera and an aperture-preferred camera can be focused mainly on the morphology of the program lines. In connection with the morphology of the program lines, so-called programmed exposure controls in a narrow sense have been suggested which rely upon a program line describing both the aperture value and exposure time varying at a fixed rate in response to variation in the exposure value or a program line describing only the aperture value varying before a particular exposure value is reached and only the exposure time varying thereafter. Varied forms of program lines on the one hand have been suggested and cameras on the other hand have also been suggested wherein a plurality of different forms of program lines are pre-prepared and optically optionally selectable to accommodate a wide range of versatile intended uses such as U.S. Pat. Nos. 4,103,307 and 4,286,849. However, the opportunity to match a user with program line suited for all of his preferences and all of his intended uses is still very low. Further, in a camera having a plurality of selectable program lines, it is quite likely that a number of program lines will be of slight or no use and would lead to an objectionable increase in the total cost of the camera and the complexity of operation.
Finally, Japanese Laid Open Patent Application No. 54-138431, which corresponds to allowed U.S. Pat. application Ser. No. 29,919, discloses a pre-stored program that can be modified. The prior art is still seeking an optimum programmable camera that can subjectively accommodate a user3 s personal demands.